I have a sparc ultra2 creator3d with 2 296mhz in my second home where there is no internet connection at all, since I am going there I would like to upgrade it offline.
So on my gentoo x86 box I changed my make.profile link to /usr/portage/profiles/default-linux/sparc/sparc64/2007.0 created a /etc/portage/package.keywords replacing ~x86 with ~sparc and finally emerge -f world. Now I am planning to burn on dvd the entire /usr/portage hierarchy (distfiles included), copy it to the sparc and emerge --update --world there.
I would of course only install the same app I have in the world file on my x86 box, and packages required by the sparc profile.
Is my plan going to work?
What about cross-compiling all packages for sparc64? I found this guide http://gentoo-wiki.com/HOWTO_Cross_Compile and http://www.gentoo.org/doc/en/cross-compiling-distcc.xml. Would it be easier to cross compile sparc packages on my x86 box connected to the internet or try to make it download all distfiles I need for my sparc machine and then compile there?

Ususally I execute emerge -f world before emerge -e world.
In this case, I have made the experience, that emerge -f world didn´t fetch all nessecary files. Sometimes emerge -f world didn´t fetch some patches.

I have also ordered a free Solaris 10 dvd, but already solaris 9 was rather slow on that old machine....
I try tomorrow the offline update method, cross-compiling an entire system is more complicated and probably doesn't work anyway.
I am pretty sure something will be missing but the ultra2 has a floppy and maybe I can download small things in an internet cafe, some also offer to burn cd usually at a high price.

This won´t work, since emerge -f world does not fetch all files and patches.

There is a syntax for SRC_URI to conditionally download based on use flags but not based on the arch I think, so unless there is a sparc use flag it shouldn't happen. Most patches are usually in the files directories directly in the portage tree